Political party targeting People with a Facebook page

We are currently in a technological age. Keeping this in mind, do you think it would be possible to assemble a political party targeting people with a Facebook page; Instagram; or Twitter? In other words, a group of political activists would develop and create a political party by reaching out to people using only social media. Pros? Cons?

2.  What incentives might influence US citizens under the age of 25 to actually join and actively participate in a political party?

3.  Two of the main roles of political parties are to take responsibility for the government and its policies as the party in power, and the party out of power is expected to provide clear opposition. Are these roles possible when we have divided government?

4.  Do you think the US will ever have one political party ( all political parties merged into one party)? Is it necessary to have more than one party?